/Engine/Plugins/FX/Niagara/Source/NiagaraEditor/Public/Widgets/SItemSelector.h
Whether or not to preserve the expansion state when refresh is called. If true, OnGetKeyForCategory and OnGetKeyForSection must be set if Categories or Sections are used, respectively.
WidgetArgsType & PreserveExpansionOnRefresh &40; bool InArg &41;